Adding two two-digit numbers

PROCEDURAL

Mathematics›Addition & Subtraction|Ages 6—7|ID: mt_UQnAFPs83F

Add and subtract two two-digit numbers using concrete objects, pictorial representations, and mental methods

Mastery Evidence

Calculate 34 + 27 using base-ten blocks or column addition
Calculate 63 − 28 using a number line or partitioning
Explain a strategy for adding or subtracting two two-digit numbers

Assessment Prompt

“Can [child] add or subtract two two-digit numbers — like '43 + 28' — using counters, a drawing, or working it out in their head?”

Curriculum Standards1 alignment

Maths/Y2/AS/6The national curriculum in England

Add and subtract two two-digit numbers

Add and subtract numbers using concrete objects, pictorial representations, and mentally, including two two-digit numbers.

Mathematics · Key Stage 1

Prerequisites2

Mental addition and subtraction (age 6+)
hardAges 6—7
Adding and subtracting tens mentally
hardAges 6—7

Show full prerequisite tree

Mental addition and subtraction (age 6+) hard
Adding two two-digit numbers requires ability to add ones to a two-digit number
- Adding and subtracting hard
  Adding ones to a two-digit number extends Y1 adding within 20
  - Number bonds hard
    Adding/subtracting to 20 procedurally requires knowing the number bonds
    - Number bonds to 9 hard
      Number bonds within 20 builds on knowing bonds to 10
      - Numbers up to 10 into pairs hard
        Making 10 is a specific application of decomposing numbers into pairs
        
        Addition as combining or putting together two hard
        Decomposing numbers into pairs requires understanding addition as combining
        
        How Many in Total? hard
        Understanding addition as combining groups requires knowing numbers represent quantities (cardinality)
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
    - Fluent adding and subtracting within 5 hard
      Recalling bonds within 20 builds on fluency within 5
      - Addition as combining or putting together two hard
        Fluency with addition within 5 requires understanding addition as combining
        
        How Many in Total? hard
        Understanding addition as combining groups requires knowing numbers represent quantities (cardinality)
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
      - Subtraction as taking away or separating hard
        Fluency with subtraction within 5 requires understanding subtraction as taking away
        
        How Many in Total? hard
        Understanding subtraction as taking away requires knowing numbers represent quantities (cardinality)
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
- The two digits of a two-digit number hard
  Adding ones to two-digit numbers requires understanding tens and ones
  - A Ten Is Ten Ones hard
    Understanding tens and ones place value requires the concept of 10 as a bundle
    - The teen numbers hard
      Understanding 10 as a bundle builds on understanding teen numbers as 'a ten and some ones'
      - How Many in Total? hard
        Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
      - Reading and writing numbers to 20 hard
        Composing/decomposing teen numbers requires reading and writing those numerals
        
        How Many in Total? hard
        Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
        
        Writing digits 0-9 hard
        Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)
        
        Sitting and holding a pencil soft
        Same motor skills for digit formation
  - The teen numbers hard
    General two-digit place value extends from understanding teen number composition
    - How Many in Total? hard
      Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities
      - One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
    - Reading and writing numbers to 20 hard
      Composing/decomposing teen numbers requires reading and writing those numerals
      - How Many in Total? hard
        Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
      - Writing digits 0-9 hard
        Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)
        
        Sitting and holding a pencil soft
        Same motor skills for digit formation
Adding and subtracting tens mentally hard
Adding two two-digit numbers requires ability to add tens to a two-digit number
- 10 More or 10 Less hard
  Adding/subtracting tens builds on mentally finding 10 more or less
  - One More Each Time soft
    10 more/less generalises the concept of one more/one less to tens
    - How Many in Total? hard
      Understanding 'one more/one less' requires understanding that each number represents a quantity (cardinality)
      - One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
  - The two digits of a two-digit number hard
    Mentally finding 10 more/less requires understanding that the tens digit changes
    - A Ten Is Ten Ones hard
      Understanding tens and ones place value requires the concept of 10 as a bundle
      - The teen numbers hard
        Understanding 10 as a bundle builds on understanding teen numbers as 'a ten and some ones'
        
        How Many in Total? hard
        Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
        
        Reading and writing numbers to 20 hard
        Composing/decomposing teen numbers requires reading and writing those numerals
        
        How Many in Total? hard
        Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
        
        Writing digits 0-9 hard
        Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)
        
        Sitting and holding a pencil soft
        Same motor skills for digit formation
    - The teen numbers hard
      General two-digit place value extends from understanding teen number composition
      - How Many in Total? hard
        Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
      - Reading and writing numbers to 20 hard
        Composing/decomposing teen numbers requires reading and writing those numerals
        
        How Many in Total? hard
        Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
        
        Writing digits 0-9 hard
        Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)
        
        Sitting and holding a pencil soft
        Same motor skills for digit formation
- The two digits of a two-digit number hard
  Adding/subtracting tens requires place value understanding
  - A Ten Is Ten Ones hard
    Understanding tens and ones place value requires the concept of 10 as a bundle
    - The teen numbers hard
      Understanding 10 as a bundle builds on understanding teen numbers as 'a ten and some ones'
      - How Many in Total? hard
        Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
      - Reading and writing numbers to 20 hard
        Composing/decomposing teen numbers requires reading and writing those numerals
        
        How Many in Total? hard
        Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
        
        Writing digits 0-9 hard
        Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)
        
        Sitting and holding a pencil soft
        Same motor skills for digit formation
  - The teen numbers hard
    General two-digit place value extends from understanding teen number composition
    - How Many in Total? hard
      Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities
      - One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
    - Reading and writing numbers to 20 hard
      Composing/decomposing teen numbers requires reading and writing those numerals
      - How Many in Total? hard
        Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)
        
        One-to-one counting hard
        Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'
      - Writing digits 0-9 hard
        Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)
        
        Sitting and holding a pencil soft
        Same motor skills for digit formation

Unlocks1

Mental and written addition and subtraction
hardAges 6—7